Setting and smashing extreme temperature records over the coming century

18 June 2019

Changes in the intensity or frequency of extreme climate events can profoundly increase the disruption caused by climate change. Unprecedented extreme events can be particularly challenging to people and ecosystems. The more extreme these events are, the greater the potential to push ecosystems and communities beyond their ability to cope.

The rate at which existing high temperature records have been broken has increased in response to rising global greenhouse gas emissions, and this is projected to increase further over the coming century.

New Earth Systems and Climate Change Hub research published today in Nature Climate Change examines future high monthly mean temperature records that will be so extreme they will not have been experienced previously. The paper provides projections of the rate of extreme high temperature record setting and record ‘smashing’ (when a record exceeds the previous record by a large amount) over the coming century.

The research found that the likelihood of setting at least one monthly record that ‘smashes’ the previous record by more than 1.0°C is eight times more likely if global greenhouse gas emissions are not markedly reduced, and over twenty times more likely than would be the case if human-caused greenhouse gas emissions had not occurred at all.

More extreme monthly mean temperature records are projected to be set under a high emission scenario (RCP8.5) than under a low emissions scenario (RCP2.6), and far more of the records will be ‘smashed’ under a high emissions scenario. In addition, the highest pace at which records will be set tend to occur in the poorest countries: approximately 70% of years will see extreme temperature records set in the world’s least developed countries and in Small Island Developing States by the end of the century, whereas this figure is only 50% in wealthier nations.

These findings highlight the benefits of reducing global greenhouse emissions by the end of the 21st century in terms of reducing the pace of extreme temperature record-setting and record-smashing.

However, the study also found that even if emissions are reduced, unprecedented monthly temperature extremes are projected to occur frequently over the coming decades. This means that people who manage systems affected by extreme temperatures will need to start considering and managing risks associated with these extreme temperatures now.